Method and Apparatus for Transmitting Signals

1. A receiving apparatus comprising: a receiving module configured for receiving one of a first and second packet signals wherein (1) the first packet signal has a first packet format which includes a first short training sequence (STS) for a MIMO system and a first long training sequence (LTS) for the MIMO system, the first STS and the first LTS being arranged in that order in the first packet format, and (2) the second packet signal has a second packet format which includes a second STS for a non-MIMO system, a second LTS for the non-MIMO system, and a third LTS for the MIMO system, the second STS, the second LTS, and the third LTS being arranged in that order in the second packet format, and wherein the first packet format includes no second LTS, the first and second STSs are for AGC estimation, the first to third LTSs are for channel estimation, the first LTS has a signal pattern which is the same as that of the third LTS, and the first STS has a signal pattern which is different from that of the second STS, said receiving apparatus further comprising a processing unit configured for processing one of the first and second packet signals, said processing unit including: an ACG module configured for performing AGC estimation based on said first STS or on said second STS, a channel estimation module configured for performing channel estimation based on said first LTS or on said second and third LTSs.